For example, to convey out an article disposed inside a chamber, a conveyance device that includes a bar for pushing out the article is used. The conveyance device inserts the bar from the front of the chamber toward the back of the chamber and pushes the article to outside the chamber by using the bar (refer to, for example, PTL 1). During insertion of the bar toward the back of the chamber, the bar passes above the article. The bar is lowered at the back of the chamber to a height that enables the bar to come into contact with the article and push out the article. A driving mechanism that changes the height of the bar may include, for example, a rack-and-pinion or may include a servo motor.